Ok, does he have a fave toy or treat or anything?? Something you can use to make him being alone a good thing.

For example, I fostered a gsd x who had SA. Her fave thing in the world was a teddy. But I only ever gave her this teddy when she was going to be left.
She soon started running to her crate quickly as soon as I got teddy out. I took him away from her as soon as I got home and took her a long walk.

x

__________________